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| author | Wollnashorn <Wollnashorn@users.noreply.github.com> | 2023-04-05 01:29:46 +0200 |
|---|---|---|
| committer | Wollnashorn <Wollnashorn@users.noreply.github.com> | 2023-04-08 16:12:30 +0200 |
| commit | 780240e6979b198e7bd10feaad5399b8b4b63762 (patch) | |
| tree | c145f48c66cf003e618cefc63496e3f5b7637f56 /src/shader_recompiler/backend/spirv | |
| parent | bbdfe1fab1f1706b7e6a62d93951bb451bbeec43 (diff) | |
shader_recompiler: Add subpixel offset for correct rounding at `ImageGather`
On AMD a subpixel offset of 1/512 of the texel size is applied to the texture coordinates at a ImageGather call to ensure the rounding at the texel centers is done the same way as in Maxwell or other Nvidia architectures.
See https://www.reedbeta.com/blog/texture-gathers-and-coordinate-precision/ for more details why this might be necessary.
This should fix shadow artifacts at object edges in Zelda: Breath of the Wild (#9957, #6956).
Diffstat (limited to 'src/shader_recompiler/backend/spirv')
| -rw-r--r-- | src/shader_recompiler/backend/spirv/emit_spirv_image.cpp | 39 |
1 files changed, 39 insertions, 0 deletions
diff --git a/src/shader_recompiler/backend/spirv/emit_spirv_image.cpp b/src/shader_recompiler/backend/spirv/emit_spirv_image.cpp index 02073c420e..968901d42b 100644 --- a/src/shader_recompiler/backend/spirv/emit_spirv_image.cpp +++ b/src/shader_recompiler/backend/spirv/emit_spirv_image.cpp @@ -261,6 +261,39 @@ Id BitTest(EmitContext& ctx, Id mask, Id bit) { const Id bit_value{ctx.OpBitwiseAnd(ctx.U32[1], shifted, ctx.Const(1u))}; return ctx.OpINotEqual(ctx.U1, bit_value, ctx.u32_zero_value); } + +Id ImageGatherSubpixelOffset(EmitContext& ctx, const IR::TextureInstInfo& info, Id texture, + Id coords) { + // Apply a subpixel offset of 1/512 the texel size of the texture to ensure same rounding on + // AMD hardware as on Maxwell or other Nvidia architectures. + const auto calculate_offset{[&](size_t dim) -> std::array<Id, 2> { + const Id nudge{ctx.Const(0x1p-9f)}; + const Id image_size{ctx.OpImageQuerySizeLod(ctx.U32[dim], texture, ctx.u32_zero_value)}; + const Id offset_x{ctx.OpFDiv( + ctx.F32[1], nudge, + ctx.OpConvertUToF(ctx.F32[1], ctx.OpCompositeExtract(ctx.U32[1], image_size, 0)))}; + const Id offset_y{ctx.OpFDiv( + ctx.F32[1], nudge, + ctx.OpConvertUToF(ctx.F32[1], ctx.OpCompositeExtract(ctx.U32[1], image_size, 1)))}; + return {ctx.OpFAdd(ctx.F32[1], ctx.OpCompositeExtract(ctx.F32[1], coords, 0), offset_x), + ctx.OpFAdd(ctx.F32[1], ctx.OpCompositeExtract(ctx.F32[1], coords, 1), offset_y)}; + }}; + switch (info.type) { + case TextureType::Color2D: + case TextureType::Color2DRect: { + const auto offset{calculate_offset(2)}; + return ctx.OpCompositeConstruct(ctx.F32[2], offset[0], offset[1]); + } + case TextureType::ColorArray2D: + case TextureType::ColorCube: { + const auto offset{calculate_offset(3)}; + return ctx.OpCompositeConstruct(ctx.F32[3], offset[0], offset[1], + ctx.OpCompositeExtract(ctx.F32[1], coords, 2)); + } + default: + return coords; + } +} } // Anonymous namespace Id EmitBindlessImageSampleImplicitLod(EmitContext&) { @@ -423,6 +456,9 @@ Id EmitImageGather(EmitContext& ctx, IR::Inst* inst, const IR::Value& index, Id const IR::Value& offset, const IR::Value& offset2) { const auto info{inst->Flags<IR::TextureInstInfo>()}; const ImageOperands operands(ctx, offset, offset2); + if (ctx.profile.need_gather_subpixel_offset) { + coords = ImageGatherSubpixelOffset(ctx, info, TextureImage(ctx, info, index), coords); + } return Emit(&EmitContext::OpImageSparseGather, &EmitContext::OpImageGather, ctx, inst, ctx.F32[4], Texture(ctx, info, index), coords, ctx.Const(info.gather_component), operands.MaskOptional(), operands.Span()); @@ -432,6 +468,9 @@ Id EmitImageGatherDref(EmitContext& ctx, IR::Inst* inst, const IR::Value& index, const IR::Value& offset, const IR::Value& offset2, Id dref) { const auto info{inst->Flags<IR::TextureInstInfo>()}; const ImageOperands operands(ctx, offset, offset2); + if (ctx.profile.need_gather_subpixel_offset) { + coords = ImageGatherSubpixelOffset(ctx, info, TextureImage(ctx, info, index), coords); + } return Emit(&EmitContext::OpImageSparseDrefGather, &EmitContext::OpImageDrefGather, ctx, inst, ctx.F32[4], Texture(ctx, info, index), coords, dref, operands.MaskOptional(), operands.Span()); |